A virtual slide is known in which pieces of partial image data obtained by imaging respective parts of a sample on a slide glass at a high resolution using a microscope are connected to obtain image data of an entire sample, so that such image data can be displayed on a display of PC or the like as a microscope image for observing.
When an image is captured with a microscope, shading occurs which means unevenness in luminosity caused by unevenness in light source, non-uniformity of an optical system, an issue of an imaging element, or the like. Where shading occurs, the more distant the place is from the optical axis, it becomes darker. As a result, in a case where pieces of partial image data are connected together like a virtual slide, failure may occur such as unnatural border generated at a border portion between pieces of partial image data, or a shading that itself looks like a pattern of a sample.
To cope with this, a method is known which involves acquiring a pattern of shading as a calibration image in advance and performing correction based on the calibration image. Patent literature 1 describes a microscope system for performing such correction, in which image data for calibration is obtained by escaping a sample when observing in transmission illumination and by reflecting light when observing in epi-illumination, so that, even if illumination unevenness changes when illumination light is switched to change shading, the shading can be suppressed. Further, patent literature 2 describes a fluorescence image acquiring device which performs imaging with a uniform fluorescence sample as a calibration sample at the time of fluorescence observation.